What are the solutions to [tex]x^2 + 8x + 7 = 0[/tex]?

A. [tex]x = -8[/tex] and [tex]x = -7[/tex]

B. [tex]x = -7[/tex] and [tex]x = -1[/tex]

C. [tex]x = 1[/tex] and [tex]x = 7[/tex]

D. [tex]x = 7[/tex] and [tex]x = 8[/tex]



Answer :

To solve the quadratic equation \( x^2 + 8x + 7 = 0 \), we will utilize the quadratic formula, which is given by:

[tex]\[ x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} \][/tex]

Here, the coefficients are:
- \( a = 1 \)
- \( b = 8 \)
- \( c = 7 \)

Step 1: Calculate the discriminant:
[tex]\[ \Delta = b^2 - 4ac \][/tex]
Substituting the values of \( a \), \( b \), and \( c \) into the discriminant formula:
[tex]\[ \Delta = 8^2 - 4 \cdot 1 \cdot 7 = 64 - 28 = 36 \][/tex]

Step 2: Compute the two solutions using the quadratic formula:
[tex]\[ x = \frac{-b \pm \sqrt{\Delta}}{2a} \][/tex]
Since \( \Delta = 36 \), we find:
[tex]\[ x = \frac{-8 \pm \sqrt{36}}{2 \cdot 1} = \frac{-8 \pm 6}{2} \][/tex]

Step 3: Calculate the two possible values for \( x \):
[tex]\[ x_1 = \frac{-8 + 6}{2} = \frac{-2}{2} = -1 \][/tex]
[tex]\[ x_2 = \frac{-8 - 6}{2} = \frac{-14}{2} = -7 \][/tex]

Therefore, the solutions to the quadratic equation \( x^2 + 8x + 7 = 0 \) are:
[tex]\[ x = -1 \quad \text{and} \quad x = -7 \][/tex]

Thus, the correct answer is:
[tex]\[ x = -7 \quad \text{and} \quad x = -1 \][/tex]

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